Sieve agitator



sept. 12, 1967 R. E. THAVCHER SIEVE AGITATOR 2 Sheets-Sheet l Filed Feb. l, 1965 Sept 12, 1967 Filed Feb. 1, 1965 E. lTHACHER 3,341,012

SIEVE AGITATOR 2 Sheets-Sheet 2 United States Patent Oiiiee 3 ,3 Patented Sept. 12, 1 967 3,341,012 SIEVE AGITATOR Ronald E. Thacher, Addison, Ill., assignor to Soiltest, Inc., Evanston, lill., a corporation of Illinois Filed Feb. 1, 1965, Ser. No. 429,359 4 Claims. (Cl. 209-315) ABSTRACT OF THE DISCLOSURE In a vibrating screen assembly of the type including a screen unit comprising one or more vertically spaced, superimposed, stacked, horizontally-disposed screen frames supported on a rotatable, eccentrically-mounted shaft, a novel, single, vertically-extending pivotal anchor post fastening the screen unit to a fixed base of the assembly, the point of attachment of the post to the screen unit being asymmetric with respect to points of support of the screen on the eccentrically mounted shaft, whereby vertical movement of the screen unit is obviated only at its point of att-achment to the single post, thereby imparting an eccentric, compound and complex, tipping and twisting action to the screen unit during operation of the vibrating screen assembly.

This invention relates to grading, sifting, screening and analogous machines. More particularly, the invention is concerned with agitating mechanisms and vibrating screen or tables having eccentric gyratory action, as well as eccentric out-of-balance action. In a preferred embodiment, the invention pertains to improvements in the art of vibrating screens or sieves for grading or separating aggregates or other materials fed to a screen or table in bulk.

For the purposes of illustrative disclosure, and not by way of limitation, the present invention will be described with reference to a vibrating screen mechanism. Such a structure includes a base or a supporting dead frame, and a live or Vibrating screen or sieve unit comprising one or more superimposed or vertically stacked screen frames or sections, the screen or sieve unit being vibrated by -a power mechanism connected thereto. It is the aim of this invention to provide a simple, practical and highly effective mechanism for intensifying the gyratory, agitating, and pulsating action of screening equipment of the nature indicated.

It is a principal object of the invention to provide a novel structural -arrangement for imparting to or impressing upon a screen assembly or table a combination of modes of gyratory action and rotation coupled with means for accentuating the over-all effectiveness of the motions imparted.

It is another object of the invention to provide a novel dual eccentric shaft for imparting gyratory and rotating motion to a tier of screens supported thereon and to provide an anchor means connected to the tier to preclude and prevent a particular mode of movement thereby accentuating other modes of agitation.

Another object of the invention is to provide a screen agitating structure in which the conjoint effect of forces applied to the screens is effective to provide improved modes of mechanical agitation to achieve enhanced operation of separators or graders and better and more efficient screening action.

Other and further objects and advantages will become apparent from a reading of the following specification taken in conjunction with the drawings in which:

FIGURE 1 is a front elevational view of the sieve agitator embodying the present invention.

FIGURE 2 is a side elevational View of the apparatus.

FIGURE 3 is a top plan view of the screening device.

FIGURE 4 is a schematic or diagrammatic representation of the side to side movement and rise and fall movement of the duo eccentric shaft creating a clockwisecounterclockwise agitation, and a corner tipping action of the sieve unit resulting from the anchor structure of the assembly.

FIGURE 5 is a front elevational view of the duo eccentric shaft of the apparatus and the stub axles corinected thereto.

FIGURE 6 is an end View of the duo eccentric shaft assembly taken on the line 6-6 of FIGURE 5.

FIGURE 7 is an end View of the duo eccentric shaft assembly taken on the line 7 7 `of FIGURE 5.

FIGURE 8 is an elevational view, with parts cut away, showing the corner anchor including the ball joints and withdrawn sockets.

FIGURE 9 is a cross-sectional view taken on the line 9 9 of FIGURE 2 and showing the manner of connecting the upper end of the anchor shaft to a corner of the sieve unit.

FIGURE 10 is a cross-sectional view taken on the line 10-10 of FIGURE 2 and showing the method of fastening the lower end of the anchor to the base of the agitator device.

The general operation of the screening apparatus of this invention involves the special unique actuating movements imparted to the screens by means of a driving mechanism and transferred through a duo-eccentric driving shaft the overall effect and action of which is modified by means of an anchor which restrains and controls movement of the screens in a given mode while accentuating agitation in other modes of vibration.

The aims and objects of the invention are accomplished by providing a sifting or screening machine in which the sieve assembly or screen units are supported at three positions, two of these positions describing similar eccentric modes in generally vertical planes but out of phase with each other, and the third support position comprising a fixed anchor fastened to the screen unit at a point spaced from the other two supports and asymmetrically located with respect thereto. The anchor permits movement of the screen unit in a generally horizontal plane but prevents or restrains motion in generally vertical planes. The overall effect is to impart to the screen unit being agitated upwardly and downwardly tilting motions and forwardly and rearwardly swinging or twisting motions symmetrical with respect to the midpoint of the base of the screen unit. The asymmetrical anchoring disrupts or interferes with what would otherwise be purely symmetrical though opposed modes of oscillation and accentuates or intensifies the agitation forces acting upon the screen unit. An understanding of all of the factors involved will be achieved upon a consideration of the following detailed description of a preferred embodiment of the invention.

Referring now to the drawings, and particularly to FIGURES 1, 2, 5, 6 and 7, for purposes of disclosure, the invention is shown as embodied in a sieve or screen agitator assembly 11 including a dead frame base, or drive housing 13 on which is pivotally and swingingly supported a tier of sieves comprising a screen unit, or a shaker assembly 15.

The base 13 may be of any preferred construction but in the example illustrated is shown as comprising a frame of steel channel construction and including base channels 20, side walls 22, and top channels 26. The base 13 is adapted for anchorage to a floor or other support (not shown) and suitable Ifeet or anges 30 are provided for anchorage purposes.

Supported on or Within the base or housing 13 is an electric drive motor 34 fastened to a wall of the housing by means of a mounting bracket 37. A drive shaft 38 of the mot-or extends transversely through a side wall 22 of the drive housing 13 and carries a pulley wheel 39.

A duo eccentric agitator shaft 40 having a pair of opposed endwardly extending coaxial stub axles 43 and 45 is rotatably journaled through its axle, 43 and 45 in a pair of bearings 47 and 49, which are in turn fastened to the top or top channels 26 of the drive housing 13 by means of suitable bolts 51. The duo eccentric shaft 40 carries a pair of laterally spaced self-aligning roller bearings 55 and 56 of a conventional construction. The sieve or screen unit is clamped or otherwise suitably fastened to the outer body or block portions of the bearings 55 and 56 so that the screen unit 15 is pivotally supported above the drive housing 13 and on the shaft 40. A pulley wheel 57 is fastened on the end of the axle 43 extending endwise of the shaft 40, and a drive belt 58 is trained over the pulley wheels 39 and 57. The pulley wheels 39 and 57 and the belt 58 are enclosed in a guard or shield 59 fastened to the sidewall of the base by means of screws 60.

As illustrated most clearly in FIGURE 2, an anchor bar or rod assembly 61 fastened at its opposite ends to a corner 62 of the screen unit 15 and to drive housing 13 obviates uncontrolled pivotal movement of the screen unit 15 about the shaft 40'and constitutes the third element of a three-point support system for the screen unit. The structure of the anchor or rod assembly 61 itself is illustrated in FIGURE 8 and the manner of its attachment to the screen assembly 15 and the drive housing 13 is illustrated generally in FIGURES l and 2 and in greater detail in FIGURES 9 and 10.

In the particular preferred embodiment shown, the anchor 61 consists of an enlarged bar, rod, or cylindrical body 66 at the opposite ends of which are a pair of rounded members or spherical yballs 71 and 72 which may be connected to or formed, in any preferred manner, on the cylindrical body 66 extending therebetween. However, in the example illustrated in FIGURE 8, the ends of the -anchor bar 66 are threaded and pinned and the threaded ends 76 and 78 are adapted to be received in mating tapped openings 82 and 84 formed in the balls 71 and 72. Prior to attachment of the second spherical member onto the end of the anchor bar 66, a pair of ball housings and bearing seat assemblies 88 and 90 having openings extending therethrough and coaxial with the anchor bar 66, and include annular bearing seats or sockets 93 and 95 and sleeve portions 97 and 99 are positioned axially on the bar 66 of the rod assembly 61. The second spherical member 72 is then fastened onto the end of the anchor bar. As shown in FIGURE 8, the housings 88 and 90 have enlarged end openings or bores 105 and 107 through which the corresponding spherical members or balls 71 and 72 may pass to seat against respective annular tapered seat surfaces 110 and 112 of the sockets 93 and 95.

The anchor holding means which comprise the ball housings and bearing seat assemblies 88 and 90 are each provided with means for firm attachment respectively to the corner of the sieve or screen unit 15 and to drive housing 13 therebelow. A preferred method of attachment is illustrated in FIGURES 2, 9 and 10. The upper housing 88 is provided with a pair of through bores 120 and 121 extending through the body 123 of the housing, and the base plate 125 of the screen unit 15 has a pair of holes drilled to align with the bores 120 and 121 of the ball housings. Threaded bolts 130 extend through the aligned bores and holes and cooperating nuts 132 are threaded in place to complete the attachment of the upper anchor hol-ding means 88 to the base plate 125 of the screen unit 15. Handles 127 attached to the sides 22 of the housing 13 facilitate the transporting of the screen agitator device or yball housing. The lower anchor holding means or ball housing is fastened to a side wall 22 of the drive housing 13 by a pair of threaded bolts 140 extending through holes 148 in the side wall and aligned with a pair of holes 155 extending through the body 153 of the ball housing 90. Nuts 158 threaded on the ends of the bolts 140 lock the ball housing 90 in place.

In order to minimize axial movement of the anchor 61 within the housings 88 and 90, and to provide resilient preloading of the anchor, a spacer block or pressure pad 170 of neoprene or the like positioned within the enlarged opening of the upper anchor holder 88 between the ball 71 and the base wall or plate 125 of the screen unit 15 urges a metallic swivel pad 173 against the ball 71 to retain and stress the ball 71 against the tapered -annular seat of the socket 93. At the lower end of the anchor 61 a retainer plate 175 is fastener across the open bottom of the anchor holder or ball housing 90 by means of threaded bolts 177 received in drilled and tapped bores 183 in the body 153 of the ball housing 90 and urges a block or pressure pad 187 of neoprene or the like against metallic swivel pad 190 to limit and control downward movement of the anchor 61 and to keep the ball 72 urged resiliently against its annular seat 112.

Referring now to the novel duo eccentric agitator shaft 40 of the invention, and particularly to FIGURES 5, 6 and 7, the shaft 40 itself is seen as cylindrical in form. However, as best shown in FIGURE 5, the longitudinal axis of the shaft 40 is tilted with respect to the end-connected coaxial st-ub axles which support the duo eccentric shaft 40 at its ends, and through which the eccentric shaft 40 is driven. This off-set structural arrangement is illustrated in the end views of FIGURES 6 and 7 which show thel80 phase relationship of the radial displacement of the agitator shaft 40 with respect to its supporting stub axles 43 and 45.

Supported on the base plate of the screen unit 15 are a plurality -of screens in superimposed stacked relation. The apertures or foramina of the screens decrease in size toward the lowest screen, the material passing through an upper screen being deposited onto a lower screen for grading the same in different sizes. Since the screens or sieves themselves do not constitute a part of the subject invention, they will not be described in further detail herein. In the particular embodiment of the invention illustrated, the adjacent framing members or side walls 198 of the stacked screens 190 are clamped and held in place by means 0f a pair of vertical hold down rods 201 and 203 fastened at their lower ends 206 and 208 to opposite sides of the base plates 125 of the screen unit 15 by means -of pivotal pins 210 and 212.'The upper ends of the rods 201 and 203 are threaded 213 and clamping arms 215 and 217 slideably positioned on the rods 201 and 203 are urged downwardly to bear against the frames 198 of the top screen and held firmly in place by means of hand screws or hold down knobs 223 and 225.

The modes of gyration, vibration, 4and agitation of the vertically stacked screens or the screen unit 15 are the resultant of the motion of the rotating duo or dual eccentric shaft on which the unit is mounted, in combination with the effect of the corner post or anchor which restains or constrains movement of the anchored corner of the screen to a generally horizontal plane. That is, the motion of the screens is determined or defined by the combined effects of the 180 phased duo eccentric rotating shaft and the novel corner anchor, the latter tending to dampen or limit vertical movement of the screens at the point of connection, while multiplying or accentuating screen movement at free corners of the assembly. An overall gyratory and twisting action is imparted to the screen unit.

The various types of movement imparted to and imposed upon the screen unit are illustrated schematically in the somewhat over-simplified diagram of FIGURE 4 wherein the lines a-a and b-b represents the 180 phased forward to rearward movement of the ends of the duo eccentric shaft combined with a rise and fall movement or tipping action (FIGURE l, lines c-c). The upward and downward movement and the -rearward and forward movement of the free corner of the screen unit diagonal of the anchored corner are indicated schematically by the lines d-d in FIGURES 3 and 4. Rise and fall movement from front to back -of the eccentric shaft results in clockwise-counterclockwise rotation of the ends of the shaft. The several action patterns described above are combined into one complete cycle per one shaft rev-olution, the lateral ends of the Iscreens being simultaneously actuated in opposite directions or 180 out of phase to describe generally circular orbits in laterally spaced vertical planes as outer principal surfaces of the duo eccentric shaft describe surfaces of revolution comprising coaxial apex joined laterally extending conical surfaces. What might otherwise be regular or relatively lsimple 180 phased motion at opposed sides of the screen unit is modified by the corner anchor to provide accentuation at positions displaced from the point of anchor connection, resulting in a compound complex agitation pattern.

It will Ibe noted from the foregoing disclosure that the screens unit are maintained in generally horizontal planes during vibration permitting perfect sizing of the material and gravitation of the material at a right angle to the moving screen members, the material being agitated and distributed over the surface of the screens.

While disclosures of preferred embodiments of the invention have been provided, it is recognized that many changes may be made and numerous details of construction may be varied through a wide r-ange without departing from the essential spirit and the underlying principles of the invention. It is, therefore, desired lby the following claims to include in the scope of the invention all such variations and modifications by which substantially the results of this invention may be obtained through the use of substantially the same or equivalent means.

What is claimed is:

1. In a vibratory screening device comprising:

a horizontally supported base,

a vibratory screen unit mounted on said base and comprising a plurality of vertically stacked screen members carried by said unit,

means for effecting vibratory operation of said screen unit and comprising an elongated substantially horizontally extending duo eccentric ended actuating shaft mounted on said base and supported thereon through a pair of coaxial stub axles extending from opposed ends of said shaft and journaled in 4bearings extending upwardly of and fastened to said base, whereby upon rotation of said actuating shaft opposed ends thereof move in a 180 phased relationship defining generally circular paths in vertical planes,

a pair of laterally spaced self aligning bearings carried on said shaft adjacent opposed eccentrically moving ends thereof and laterally spaced connector means coupling said bearings with said screen unit to support said unit on said shaft, the improvement comprising anchor means asym'metrically positioned with respect to said laterally spaced bearings and extending between said base and one corner only of said screen unit to restrain said corner of said screen unit against substantial movement in a vertical plane while permitting reciprocating motion of said corner of said screen unit in generally horizontal planes, thereby establishing an eccentric, out of balance, tipping action of said screen unit and intensifying and accentuating agitation forces and screen movement at free corners of said screen unit to impart a compound and complex gyratory and twistin-g action to said screen unit.

Z. In screening apparatus of the class described and including a supporting frame and a vibratory screen assem- =bly associated with said frame, a duo eccentric elongated shaft supported rotatably on said frame and supporting said screen assembly above said frame,

said shaft being cylindrical in form and connected at opposite ends to a pair of spaced longitudinally extending coaxial stub axles,

a first of said stub axles being joined to one end of said shaft a given distance above the longitudinal axis of said cylindrical shaft and a second of said stub axles being joined to the other end of said cylindrical shaft the same said given distance below said longitudinal axis of said shaft, and

drive means to rotate said stub axles and to rotate said shaft attached thereto, rotation of said coaxial stub axles and said shaft causing said one end of said shaft to move downwardly and forwardly at the same time that the said other end of said shaft moves upwardly and rearwardly,

said rotation of said stub axles and said shaft connected thereto causing opposite ends of said shaft to describe the same mode of eccentric cycle about the axis of said stub axles but out of phase, the improvement comprising restraining means mechanically coupling said screen assembly to said frame at only one corner thereof to restrict movement of said corner to only substantially horizonal planes and to preclude substantial vertical movement of said corner.

3. In a screening device including a base, a screen unit comprising a plurality of superimposed screens having foramina progressively reduced in size downwardly, means for pivotally supporting said screen unit on said base for agitation of said screen unit to effect grading of particulate material delivered to said screening device, and drive means for agitating said screen unit, the improvement wherein said means for pivotally supporting said screen unit comprises the combination with a duo eccentric ended horizontally extending rotatable shaft for simultaneously gyrating opposed lateral ends of said screen unit supported thereon in opposite directions, of a single vertically extending pivotally mounted anchor post positioned asymmetrically with respect to ends of said shaft and extending between said screen unit and said base and connected thereto at opposed ends of said post, said post comprising means precluding substantial vertical movement of said unit at only the point of attachment to said post while permitting oscillating movement of said Screen unit in `generally horizontal planes.

4. In a vibrating screen apparatus including a base, a screen unit, support means for supporting said screen unit on said base, and drive means for agitating said screen unit, the improvement wherein said support means for supporting said screen unit on said base comprises the combination of a horizontally disposed duo eccentric ended `driven shaft and a single vertically disposed anchor post positioned asymmetrically with respect to ends of said shaft,

a pair of laterally spaced bearings fixed on said base for supporting end connected coaxial stub axles of said shaft, said bearings rotatably supporting said shaft at said coaxial stub axles thereof,

a pair of self aligning bearings mounted on said shaft adjacent opposed eccentric end portions thereof and pivotally supporting said screen unit above said shaft,

means pivotally attaching opposed ends of said anchor post to said base and to said screen unit,

said anchor post being fastened at respective opposite ends thereof to said base and to said screen unit and disposed to precludeV substantial vertical movement of only that portion of said screen unit there 7 3 adjacent While permitting unrestricted movement of FOREIGN PATENTS said screen unit in generally horizontal planes. 138,160 10/1901 Germany.

References Cited 733,976 10/ 1932 France.

UNITED STATES PATENTS l5 HARRY B. THORNTON, Primary Examiner.

1,997,392 4/1935 Piper 209-332 X R. HALPER, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No. 3,341,012 September l2, 1967 Ronald E. Thacher lt is hereby Certified that error appears in the above numbered patent requiring correction and that the Said Letters Patent should read as corrected below.

Column 3, line 8 for "axle" read axles line 35, for "enlarged" read elongated Column 6, line 45, for "positioned" read located Signed and sealed this 14th day of January 1969.

(SEAL) Attest;

EDWARD J. BRENNER Commissioner of Patents Edward M. Fletcher, Jr.

Attesting Officer 

3. IN A SCREENING DEVICE INCLUDING A BASE, A SCREEN UNIT COMPRISING A PLURALITY OF SUPERIMPOSED SCREENS HAVING FORAMINA PROGRESSIVELY REDUCED IN SIZE DOWNWARDLY, MEANS FOR PIVOTALLY SUPPORTING SAID SCREEN UNIT ON SAID BASE FOR AGITATION OF SAID SCREEN UNIT TO EFFECT GRADING OF PARTICULATE MATERIAL DELIVERED TO SAID SCREENING DEVICE, AND DRIVE MEANS FOR AGITATING SAID SCREEN UNIT, THE IMPROVEMENT WHEREIN SAID MEANS FOR PIVOTALLY SUPPORTING SAID SCREEN UNIT COMPRISES THE COMBINATION WITH A DUO ECCENTRIC ENDED HORIZONTALLY EXTENDING ROTATABLE SHAFT FOR SIMULTANEOUSLY GYRATING OPPOSED LATERAL ENDS OF SAID SCREEN UNIT SUPPORTED THEREON IN OPPOSITE DIRECTIONS, OF A SINGLE VERTICALLY EXTENDING PIVOTALLY MOUNTED ANCHOR POST POSITIONED ASYMMETRICALLY WITH RESPECT TO ENDS OF SAID SHAFT AND EXTENDING BETWEEN SAID SCREEN UNIT AND SAID BASE AND CONNECTED THERETO AT OPPOSED ENDS OF SAID POST, SAID POST COMPRISING MEANS PRECLUDING SUBSTANTIAL VERTICAL MOVEMENT OF SAID UNIT AT ONLY THE POINT OF ATTACHMENT TO SAID POST WHILE PERMITTING OSCILLATING MOVEMENT OF SAID SCREEN UNIT IN GENERALLY HORIZONTAL PLANES. 